Mount support



Oct. 16, 1945 L. E. HARDING MOUNT SUPPORT Filed March 22, 1944 lNVENTORLLOYD E HARD/N6 I subjected to shock and vibration, more'particuthecollar or ring'used-as amounting plate atmounted-system has a naturalperiod of vibration and equipment approaches that of the disturbinglflll171151) S"'l-A"lES PATIENT]. OFFICE I Mom'surron'r I Lloyd E.HardinIaBl'adleyfBeach, N. J.) alsllnor of one-filth ,to. Edmund J.Lada, Woodhaven, N. Y., andone-fli'th to William A.'Zalesak,

UW NJSF 1 Application March 22,1944, Serial ndsz'asss v c J "Accl im.(omen-s58) W My invention relates to mounts for equipment bonded to ametal collar, or ring at its edges and larly to improved methods forresiliently-supporttached to a'stationarysupport. A centrally poingequipment and for, damping 'vibratio sitioned rod or tube is bondedtothe rubber at the The present application is an improvement over '5center. of the rubber disc or plate and to this is the device shown andclaimed in my copending secured the load equipment. which is to beproapplication, Serial, No. 513,848, filed December tected againstvibration and shock. The shock 11, 1943. r absorbing action is supposedto result from flex As is well known in connection with supporting ofthe rubber disc and the diaphragm-like ing equipment, two typesofjdisturbance must be motion as the load is set into vibration orsubprovided'for, that is the so-called steadystate viiected to shock. cbration and shock. Vibrationis anoscillatory I 'Whilethistype of shockabsorber provides a condition which exists over a period voi? timefandsolution for the question of size, it does not have it has thecharacteristic of a sine wave or a comthe energy dissipating abilitiesof the piston type bination of sine waves. l 1-1 1 l5 shock absorber.Further, if: it happens that the It is also well known that everyJresiliently natural frequency of the vibration of the mount at'whic'hit will oscillate before coming to rest if' shock, resonance isestablished and the mount subjected to an impulse. Normally whensubbecomes useless and may even cause the equipiected to shock,oscillation at this natural fre- 2o ment-supported asaload todestroy'itselt. While quency occurs for a very short period. However,the last mentioned form or absorber can be deif'excited by a source ofsteady vibration of the signed to isolate vibration of the load over acernatural frequency of the'mount. violent oscillatain range offrequencies, it cannot at the same tion of the mounting systemwill-occur. These time be designed to protect against shock in adtypesof vibration-present different problems in dition to the vibration, forexample, when it is protecting equipment against vibration and shock.used in'connection with planes which are sub- Viscous damping has beenfound to be an exjected to landing shocks, where a shock mount iscellent means to neutralize vibration and to proneeded to dissipateenergy over a wide range of videshock isolation. A familiar form of suchvisfrequencies, and limit amplitude of movement at cous damping deviceis the hydraulic shock abso the resonantfrequency of the mount. sorberwhich makes use of a pistontravelling in Again in connection with therubber mounted a cylinder and displacing afluid through apersupport,rubber shoulders are provided which act tures in the piston or by meansof side vents or as bumpers when the shock received is greater pipesconnecting the two ends of the cylinder. than that for which the mountwas designed. The cylinder is attached to one unit of the mov- Withoutthe provision of a bumper'shoulder, the ing parts, while the piston isattached to the other. load would. move beyond the permissible limitsMovement of the two parts with relation to each and perhaps tear itselfloose bytearing the rubother is retarded, slowed down or damped by theber from its bond with the metal, or tearing the piston action ondisplacing the fluid from one secrubber itself. The action of theequipment hittion of the cylinder to the other. In this oper- 40 .tingthe bumper, however, results in damage to ation work is performed inforcing fluid through the equipment. vents and energy of the shock orvibration is dis- The two methods of reducing vibration transsipated.mission are the so-called isolation type and the There are, however,practical objections to this absorption type and the differencebetweenthe type of shock absorber. The maintenance cost is 4 two is clear.Isolation means the storing 01' vihigh, as is thecase with anyconstantly acting debrational energy during one part of a cycle and vicewhere there is close tolerance between two release during another partas where resilient moving members. In certain types of equipment mountsare used. Absorption is referred to as it is not possible to make a unitof smal1 enough having. a damping effect on the vibrating system size tofit it to the design or the space available. and converts energy intoheat. Absorption re- One form ofdevice has been developed to reduces themotion, of the mounted system when place the damping shock absorberdescribed. It the action of resilient elements would increase makes useof rubber or rubber-like material made the motion as in the case ofresonance, transient up into mounts and used either with rubber ineffects or rebound. However, whenever a reshear or in compression. Arubber disc or plate is 56 silient support or mount is used to reducevibraness of such reduction.

- support the load,

a damping efiect detracts from the effective- Resilient material, suchas rubber, has only a limited absorptive capacity.

tion,

The addition of means for absorbing shock to a resilient mount can undercertain conditions be beneficial. It would, therefore, be desirable tohave a mount arrangement which will resiliently but have a pronounceddamping effect only at the resonant frequency or when shock isexperienced.

It is, therefore, a principal object of my invention to provide animproved type of mount for resiliently supporting equipment which willdissipate shock energy andlimi't amplitude of movement at resonantfrequency. y

. nant frequency or on shock.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims, but theinvention itself will best be understood by reference to the followingdescription taken in connection with the accompanying drawing in whichFigure 1 is a longitudinal section of a mount-support made in accordancewith my invention in a positionof rest, Figure 2 is a transverse sectiontaken along the line 2 2 of Figure 1, Figures 3 ber a ring-like element2! bonded to a resilient diaphragm 22, which is in turn bonded to aninner ring-like element or flange 23 provided with a plurality ofapertures 24 and a central 2| are a plurality of apertures or ports 26,some e of which are-closed by spring leaf member 21 and 4 show detailsof the device shown in Figures 1 and 2 during operation, Figures 5 and 6showfurther details of the device shown in Figure 1 during operation,and Figure 'I is a longitudinal section of the mount support shown inFigure 1 when placed under load.

In accordance with my invention I provide boththe advantages of rubbermounting, per-- mitting small compact units, andalso utilizing viscousdamping to dissipate shockenergy 'at. only such .times as the load issubjected to shock or vibration at the natural frequency of the mountand supported load.

In accordance with my invention I provide a pressures. 'While oilchamber including a bottom cup-shaped portion 9 and an upper portion Hisecured thereto in any well-known manner, such as'welding or bolting;

' Mounted within the chamber and axially thereof for vertical andlateral movement is a. central element which may be a tube, a rod orasleeve ll having secured to its lower end an element 12 provided with aflange l3. The lower end of the element H and the upper surface of theflange l3 provide shoulders on opposite sides of the restricted orreduced portion I4 and having spe- 7' ciflc functions as willbedescribed. I

The post llhas bonded to it a transverse re-' 'silient element. l5,which in turn is secured to a cover plate; 16 sealed for example as bywelding to the 'upperportion l0 of-the chamber. Thus the post H isresiliently mounted at the top of the device{ The unit-may be supportedon a stationary mounting bracket H, for example, by

nuts and bolts l8 and I9 and the unit supporting the load 20 may besecured to the post member l l by the bolt 20'.

In accordance with w my invention I mount-between the upper and lowerhalves of the chainwhich may be welded to the under side of the ring,and the others closed by means of spring lea! member 21' welded to thetop of the ring. The parts may be given a flared shape as shownto-decreaseturbulence. Fluid, such as oil, may be introduced into thechamber through port 28.

As shown in Figures 3 and 4, the central post II and the load '20 mayhave relative movement with respect to the mber 23 and diaphragm 22withoutin any way e ecting movement or movement to only a slightextent-inasmuch as little if any fluid 29 is displaced during normaloperation from one side of the diaphragm to the other. Thus the deviceunder these conditions produces an approximation of a free body'so thatvibratory forces are isolated from the load or equipment being supportedand the full benefit of the'mounting for these operating conditions isrealized without detracting from the effectiveness of the isolationaction by a damping action.

If, however, the support and the load are subjected to shock the forcesproducing relative movement between the load and its support increasethe movement of the post ll so that the shoulders provided by the post Hand flange l3 alternatively engage the ring member 23, bringing intoaction the damping efiect of the diaphragm 22. As the post H and load 20move downwardly with respect to to the upper side, producing a dampingaction. Normally-the flow will be through the apertures or parts 24 ofthe central .ring member 23 and in case of excessive shocks where largepres-v sures are built up the spring leaf elements'2'l' and 21' act asindicated to relieve these excess the ring or disc 23. "When theimpressed frepressed amplitude.

quenciesapproach the resonant or natural frequency of the moun thevertical movement of the post increases until the shoulders engage thedamping disc, causing the disc and diaphragm to move up and down againstthe damping action of the fluid moving through the ports and duringother conditions through ports26.- Tests on equipment of this kind haveshown that the maximum amplitude at the resonant frequency'has beenlimitedto 1.4 times the immaximum, amplitude at resonant frequencyreaches twenty timesthe impressed amplitude,

which is the cause ofwrecked equipmentordamaged loads.

Thus, good isolation'from vibratiorijis obtained under other thanresonant frequency and-shock, v and at resonant frequency and shock thedamp ing action limits the amplitude. I While I have indicated thepreferred embodiments of my invention of which I am now'aware and havealso indicated only one specific applicathe chamber, fluid. is forcedfrom the under side of the diaphragm This action is illustrated inFigure '2.

Without this action the gated'rod-like load supportin element supportedby said resilient portion and having axial move-.

tion for which my invention may be employed, it will be apparent that myinvention is by no means limited to the exact forms illustrated or theuse indicated, but that many variations may be made in the particularstructure used, and the purpose for which it is employed withoutdeparting from the scope of my invention as set forth in the appendedclaims.

WhatIclaim as new is: I i

1. A mount for supporting a load subject to vibration and shock andincluding a member to be fixed to a load and having axial movement, asupment, the inner. end of said rod-like load supportingelement-beingprovided with a restricted shaped member into which the rod-like loadsupporting element adapted to'besecured to'a fixed support and having ,acentral opening, and resilient means fixed between said member and saidelement and resiliently supporting. said member within said opening,,means' associated with said member and said element and providingviscous damping, said means including an apertured element and apot-shaped element containing fluid and within which said aperturedelement is mounted for axial movement, said fluid having accesstoopposite sides of said apertured element through said apertures andmeans for causing said apertured element to have axial movement onlywhen the supported load is subjected to v movement beyond predeterminedlimits due to its natural frequency of vibration or to shock.

2. A mount for supporting a load subject to vibration and shock andincluding a, cup-shaped member closed at one end by a transverseflexible resilient member, an elongated rod-like load supporting elementpositioned centrally of said resilient member and extending axially intosaid cup-shaped member, the inner end of said rodlike load supportingelement being provided with a restricted portion for providingoppositely disposed shoulders at either end of said restricted portion,a transverse diaphragm extending across fluid having access to oppositesides of said diaphragm through said apertures, said diaphragm havingmovement only when the shoulders of said load supporting element engagesaid apertured means.

3. A mount for supporting a load subject to vibration and shock andincluding a member having a transverse flexible resilient member, anelongated rod-like load supporting element positioned centrally of saidresilient member and axially movable, one end of said rod-like loadsupporting element being provided with a restricted portion forproviding oppositely disposed shoulders at either end of said restrictedportion, a cup-shaped member, said load supporting element extendinginto said cup-shaped member, a transverse diaphragm extending acrosssaid cupshaped member and having means provided with apertures andsurrounding and closely adjacent said restricted portion of saidrod-like load supporting element and having relative motion with respectthereto, and a fluid within said cupshaped member, said fluid havingaccess to opposite sides of said diaphragm through said apertures, saiddiaphragm having movement only when the shoulders of said loadsupporting element engage said apertured means.

4. A mount for supporting a load subject to vibration and shock andincluding a member having a transverse flexible resilient portion, anelonporting element-extends, a transverse diaphragm extending acrosssaid cup-shaped member and having apertures therein, said loadsupporting element extending through said diaphragm and having relativemotion with respect thereto. and

a fluid within said cup-shaped member, said fiuid 1 having access toopposite sides of said diaphragm through the apertures thereof, saidrod-like load supporting element having means for engaging saiddiaphragm, said diaphragm having move- 1 ment only when the means ofsaid load supporting element engage said diaphragm when said loadsupporting element moves beyond predetermined limits. 1

5. A mount for supporting a load subject to vibration and shock andincluding a cup-shaped member having. a fluid therein, an elongatedrodlike load supporting element positioned centrally of said cup-shapedmember and extending axially into said cup-shaped member, and meansincluding resilient means extending between said cup-' shaped member andsaid elongated rod-like load supporting element, the inner end of saidelongated rod-likeload supporting element having a portion of reduceddimensions andprovided with shoulders-at either end of the reducedportion,

' a diaphragm extending transversely of said cupshaped memberintermediate said cup-shaped member and including a ring-like 1 membermounted in the walls of said cup-shaped member and extending toward saidrod-like load supporting element, an inner ring-like member mountedwithin the reduced portion of said rod-like load supporting element andhaving relative movement with respect therewith, said ring-like membersbeing provided with apertures and a resilient diaphragm connectedbetween said ring-like members, said shoulders engaging said innerring-like member when the resonant frequency of vibration of thesupported load or shock cause movement beyond predetermined limits ofsaid rod-like load supporting element with respect to said cupshapedmember, and resilient means closing the apertures in the ring-likemember supported from the wall of said cup-shaped member which functionwhen excessive pressures are developed in the fluid in said cup-shapedmember.

6. A mount for supporting a load subject to vibration and shock andincluding a member having an opening therein, an elongated rod-like loadsupporting element positioned centrally of said opening, resilient meansextending between said member and said elongated rod-like loadsupporting element, one end of said elongated rod-like load supportingelement having aiportion of reduced dimensions and providedwith'shoulders at either end of said reduced portion, a cupshaped memberintowhich said load supporting element extends, a diaphragm extendingtransversely of said cup-shaped member intermediate and including a,ring-like element mounted in the wall of said cup-shaped member andextending toward said rod-like load supporting element, an innerring-like member mounted within the reduced portion of said rod-likeload supporting element and having relative movement with respecttherewith, said inner ring-like member being provided with apertures anda resilient diaphragm connected between said rlngf-like members, saidshoulders engaging said inner ring-like member when the resonantfrequency or vibration of the supported load or shock causes movement ofsaid rod-like element beyond predetermined limits with respect to saidcup-shaped member.

'7. Amount for supporting a load subject to vibration and shock andincluding a member having an opening therein, an elongated rod-like loadsupporting element positioned within said opening and having axialmovement therein, re-

- silient means extending between said member and quency of vibration ofthe supported load or shock causes movement of said rod-like elementbeyond predetermined limits with respect to said cupshaped member.

8. A mount for supporting a load subject to,

vibration and shock and including a member hav ing an opening, anelongated rod-like load supporting element positioned within saidopening and having axial movement, resilient m'eans extending betweensaid member and said elongated rod-like load supporting element, acup-shaped member into which the rod-like supporting elenent extends, aresilient diaphragm supported by and extending transversely of saidcup-shaped member and through which the rod-like load supporting ele--ment extends, said rod-like load supporting elementand diaphragm havingrelative movement, and means on said rod-like load supporting ele-] mentfor engaging said ring-like member, said ring-like member being providedwithapertures,

said ring-like member being engaged only when the resonant frequencyofvibration of the supported load or shoot causes movement of saidrod-like load supporting element beyond predetermined limits withrespect to said cup-shaped member.

9. A mount for supporting a load subjected to vibration and shock andincluding a member to be fixed to a load and subjected to axialmovement, a supporting element adapted to be secured to a fixed supportand provided with a central aperture and resilient means fixed betweensaid member and said element and supporting said member within saidaperture, andemeans associated with said member and said element andproviding viscous damping, said means including a hollow membercontaining a fluid, said axially movable member extending withinsaidhollow member, a transverse flange submerged in said fluid for movementwithin said fluid, said axially movable member extending through saidflange and having relative movement therewith, and

means on said axially movable member for causing said flange to haveaxial movement only when said axially movable member is subjected tomovement beyond predetermined limits.

10. A mount for supporting a load subjected to vibration and shock andincluding a hollow member adapted to be secured to a. fixed support, a

. load supporting member to be fixed to a load and including a ring-likevmember subjected to axial movement and extending within the hollowmember, a resilienttransverse diaphragm at one end of said hollow memberand connected between said hollow member and said load supportingmember, a second resilient diaphragm extending between said hollowmember and said load supporting member, a transverse flange within saidhollow member and extending transversely of the load supporting member,said hollow member containing liquid inwhich said transverse flange issubmerged and provides viscous damping, said load supporting memberextending through said flan e and having relative movement therewith,and means on said load supportingmember "forengaging said flange forcausing movement-of said flange only when the supported load issubjected to movement beyond predeterminedlimits.

LLOYD E. HARDING.

